The propane industry’s weird obsession with school buses, explained

A giant pollution cloud is being emitted from a diesel-run school bus. The cloud surrounds a line of children just behind it.
Jared Bartman for Vox

Electric school buses are better for kids’ health. The propane industry has other ideas.

Last year, the popular children’s magazine The Week Junior advertised a contest called “Be Like Jack” that would award $2,000 to the preteens or teens who submitted the winning ideas for an environmental project. A few dozen kids from around the country participated, submitting proposals meant to boost sustainability in their elementary or middle schools. A Colorado 9-year-old won the grand prize for her tree-planting project.

To celebrate her win, Emily Calandrelli, host of the Netflix science show Emily’s Wonder Lab, visited the winning school during a science assembly that touted, of all things, the environmental benefits of a propane-powered school bus.

But why propane? And why there? The assembly begins to make sense considering that the sponsor behind the contest was the Propane Education Research Council (PERC), an arm of the fossil-fuel industry. PERC held the contest, a spokesperson told Vox, to “educate school children about energy options.”

America’s school bus fleet is on the cusp of a transformative shift: Historically and still predominantly powered by diesel fuel, the humble and iconic yellow buses expose some 25 million school-aged children to ultrafine particles, sulfur oxides, and nitrogen oxides — all closely linked to asthma, respiratory illness, lung disease, and cancer, according to the Environmental Protection Agency and the American Cancer Society.

To make school buses better for the climate and for kids’ health, the federal government and states are pushing to electrify their fleets. Virtually all of the nation’s 500,000 school buses are expected to turn over in the next 15 to 20 years, but EV buses are still in their infancy: There are nearly 6,000 electric buses on the road today or planned soon, making up just 1 percent of the auto total sector, according to World Resources Institute, a nonprofit research organization. With new incentives, federal regulations, and zero-emissions state targets, that portion of EV school buses is projected to grow 20 percent. The Bipartisan Infrastructure Law alone devotes $5 billion in the next five years to cleaning up school bus pollution.

A drawing of a school bus connected to a huge propane tank.
Jared Bartman for Vox

But even with federal subsidies, this shift to EV buses will be expensive, especially for public school districts, and the propane industry sees an opportunity to seize a share of the auto sector. Its representatives are working hard to convince public officials to switch to propane-fueled school buses, which they claim are “near-zero emissions” vehicles that are better for kids and the climate.

Except — that’s not true. Propane is still a polluting fuel: While it is refined differently than diesel and natural gas and combusted in uniquely styled engines, it still has a measurable impact on air quality and the climate. If PERC’s deceptive marketing to children, parents, and school administrators is successful, the propane industry threatens to lock in fossil fuels and their polluting emissions for another generation of schoolchildren.

The shift from diesel, explained

Carmen Cortez has spent much of the last two decades of her career as a driver behind the wheel of a diesel-fueled school bus. Drivers like Cortez, bus monitors, and parents are exposed to the pollution daily, alongside schoolchildren.

Yet diesel engines — which generate more power for a heavy car compared to traditional gasoline — have been inextricable from the experience of riding or driving a school bus. “Some of the students would complain because they’d smell the diesel,” she said. Sometimes those kids’ parents would take their concerns about pollution exposure to school administrators.

Two years ago, though, this changed for Cortez. Maryland’s Montgomery County public school district, a northwest exurb of Washington, DC, where Cortez works, was selected to pilot the largest electric fleet in the country, with 86 buses. “I resisted at first, because I didn’t know what this change meant for my job,” Cortez wrote in La Opinión, a Spanish-language daily newspaper and website based in Los Angeles. (The article was translated to English by a Vox editor.)

But Cortez changed her mind and, in 2022, joined EcoMadres, a Latino program of the environmental group Moms Clean Air Force. “I realized that we are at the frontlines of a transition in the transportation sector, and that I could be a part of this process and help improve the health of the students in my district, my own health, that of my community, and of the planet.”

Particulate matter, of which diesel combustion is a major source, contributes to roughly 15,000 premature deaths annually, according to EPA estimates. In some areas exposed to heavy diesel truck pollution, like near busy highways, the mortality levels from bad air are akin to those from traffic accidents and second-hand smoke. Emissions collect inside passenger cabins, elevating concentrations of particulate matter and air toxics somewhere between four and 12 times than would normally occur. And it’s not uncommon for a caravan of school buses to be traveling to a field trip or for an event, creating a cloud of emissions that also affects surrounding people in cars and communities. Higher levels of fine particulate matter and carbon were also found in school buses compared to air pollution in vehicles driving in front of the buses during a 2008 study in Seattle.

Diesel also causes students to miss more days of school. A randomized study published in the journal Nature Sustainability found replacing all pre-2000 school buses with newer models would lead to 1.3 million additional days of attendance from students each year.

Decades of research on the pronounced effects of diesel have led federal regulators to try to reduce these emissions, including in school buses. Over the past two decades, the EPA has implemented policies that require stricter tailpipe standards for diesel engines, and offered grants to buy more efficient engines.

But cost and technology has always been a barrier to a swift transition. The diesel model remains the cheapest option, making it difficult for budget-strapped public schools to shift away from them. An electric school bus can cost anywhere between three to four times that of diesel, making the cost of transition prohibitive without help. It’s what makes government support so critical to giving the sector a lift.

Such government support exists now — spurred in the first place by a scandal: In 2015, the auto company Volkswagen came under fire for lying about the emissions its diesel cars created. You may remember: After it came to light that the company had installed illegal software on a half-million diesel-burning vehicles to trick emissions tests, Volkswagen pleaded guilty to federal charges, ultimately settling for $14.7 billion — a big payout that drove the first real evolution toward electrifying the school bus.

Of the settlement, $3 billion was allocated for transportation projects around the country that would slash diesel pollution. The catch? States got to decide how they wanted to use that money, with many opting for incremental gains: Arizona, for example, spent $38 million of its share of the VW settlement to replace 330 older diesel buses with more efficient, but still diesel-running, models.

A gas stove with its signature blue-tinged flame.
SOPA Images/LightRocket via Getty
Propane is typically used for heating, cooking, and grills. It’s less common in the transportation sector, except when it comes to school buses.

The settlement funds set the contours for the fight over the school bus today. Diesel remains the cheapest on the market, making a transition only possible with government support. But only a few of the programs explicitly mandate where this funding should go. The 2021 Bipartisan Infrastructure Law created a $5 billion EPA Clean School Bus program, establishing two pots of funding: one meant only for electric buses and a second that could apply for alternative fuels or EVs. The Inflation Reduction Act also makes billions potentially available for the school bus transition, which is eligible through the Clean Heavy-Duty Vehicles program that replaces diesel with zero-emissions electricity. And while New York recently passed a law directing state funding to EVs only, other states such as Texas still create incentives for competition between gas, propane, and EVs.

That leaves a lot of discretion to states on how to spend limited pots of funding.

Enter … the propane industry.

Many Americans, some 50 million households, have a relatively limited relationship with propane that begins and ends with the burger, hotdog, or corn husk on their barbecue gas grills. Beyond its most popular use, the liquified product of petroleum gas additionally heats approximately 12 million homes that use propane fuel where natural gas infrastructure doesn’t exist. Very few people — less than 1 percent — fuel their vehicles with an alternative like propane, according to data from the Energy Information Administration.

But the propane industry sees a chance to grow its share of the auto sector by locking in school districts. And if you use a propane grill, fees on the fuel you buy are driving campaigns that don’t just include school assemblies, but other advertisements and influencers aimed at convincing kids, parents, and school officials to invest in the propane school bus.

The propane industry has targeted schools and public officials in a national campaign since at least 2018. Internal industry documents obtained by the renewables advocacy group Energy Policy Institute and reviewed by Vox show how propane, like other fossil fuel arms, has viewed the climate electrification movement as a key threat.

The Propane Education and Research Council, a federally created trade association, has a $47 million budget, funded from the half-cent fee it collects from every gallon of propane fuel sold, to support its public education campaigns. Beyond having a deep war chest to fuel its disinformation campaign, the industry has economics on its side, too: Propane-fueled buses cost significantly less than EVs, which come with a price tag of $350,000 and up.

The bus models themselves are more expensive, and districts also need to train staff and maintenance workers, as well as add transmission lines to lots for charging stations (many school districts work with contractors for their bus fleets). Another current limitation is models on the market today tend to run the battery out after about 100 miles, so the EV bus is not practical for longer commutes or field trips.

“If somebody handed me an endless amount of money, and said ‘electrify your entire fleet tomorrow,’ there will be some routes that would be challenging to electrify today,” said Jacqueline Hayes, Boston School District’s deputy director of transportation. “But we’re pretty confident that technology is going to get there in the next five years. I’m focusing on the parts of the problem I can solve today.”

But advocates say electrifying the school bus is feasible in most of the country, where routes usually run shorter than 100 miles — as long as there’s funding for the upfront costs. Less costly maintenance, EV proponents argue, is also a benefit.

“The maintenance is probably about a third of the cost of a combustion engine vehicle,” said Duncan McIntyre, CEO of Highland Electric Fleets, a company that contracts services for electric school buses. “The engine and the batteries are the same used in electric transit, like city buses. Some of those city buses have gone 250,000 miles without needing much by way of repairs. So, we have some good data as an industry and evidence that these vehicles will last a long time.”

Electrification advocates concede that cost is the biggest barrier. “We’ve not yet gotten to the tipping point where school buses are cost competitive on their own, so you do need those incentives to buy down that cost,” said Sue Gander, the director of World Resources Institute’s Electric School Bus Initiative.

Still, beyond just the cost, PERC claims that propane fuel is the most environmentally friendly solution. PERC likes to cite an industry-funded study that draws a sharp contrast with diesel, showing that propane burns 95 percent fewer nitrogen oxides than diesel. In fact, the same study showed propane could be worse than diesel when it comes to carbon dioxide and carbon monoxide emissions.

The industry frequently uses the phrase “near-zero emissions” to describe the propane bus. This is disingenuous. The EPA recognizes that propane buses produce some lower emissions, like nitrogen oxides, than other fuels, but they still do pollute. Propane still emits many of the same hazardous pollutants as diesel, and the industry fully ignores the toll of greenhouse gas emissions. The US Department of Energy’s National Lab modeled emissions of propane compared to post-2010 diesel buses and found they “do not offer significant air quality benefits.” A 2023 analysis from the World Resources Institute found no benefits of propane over diesel when it comes to climate pollution. The industry’s claims are egregious enough that even some of its own allies, including manufacturers of propane buses themselves, have called out the misinformation.

Kamala Harris with kids in front of an electric school bus
Getty Images
Vice President Kamala Harris visited a high school in Virginia to mark the first round of funding available from the $5 billion Clean School Bus Program, established by passage of the bipartisan infrastructure bill.

“Propane school buses are being lauded as the cleanest in the industry,” said Caley Edgerly, a former president and CEO of Thomas Built Buses in a blog post in 2018. “We produce propane school buses, so of course we would stand behind that statement if it were true. Unfortunately, we can’t unequivocally say that propane is the cleanest fuel for school buses today.”

PERC stands by its marketing. PERC’s Senior Vice President of Communications Erin Hatcher emailed Vox that propane “is designated a clean alternative fuel by the Environmental Protection Agency (EPA).” She added: “Propane buses produce much fewer NOx [nitrogen oxide] emissions than diesel, as you pointed out, and virtually zero particulate emissions. They also run much more quietly. When it comes to student health, these are relevant facts that show propane’s advantages when compared with diesel.”

The bottom line: Propane appears better — and only incrementally so — when compared to diesel, which is more polluting. Perpetuating disingenuous claims in schools appears to be one of PERC’s strategies to fight off electrification. After the EPA’s Clean School Bus funding was established in 2021, PERC expanded its campaign from a two-month blitz to a larger year-round effort. PERC has paid influencers including Netflix’s Calandrelli, HGTV’s Matt Blashaw, and celebrity chef Dean Sheremet to speak out against electric heat pumps and electric stoves, often in sponsored segments on local television (or to kids during a Colorado school assembly).

“PERC believes that propane-powered buses offer advantages over diesel buses, and we willingly share that information,” Hatcher said in PERC’s email to Vox. “We believe that school transportation officials need to have the best information available to them when contemplating options for replacing diesel buses, and we see propane buses as a viable option particularly in areas where electric buses are less feasible.”

In 2023, the group plans to spend $13 million on an anti-electrification campaign, including $600,000 on influencers, according to the New York Times. PERC spent at least $1.2 million from 2018 to 2019 alone on outreach targeting school transportation directors, school board members, and school business officials — an audience they’d like to buy into propane.

The momentum for EVs may be shifting

One place that had appeared to clinch a major victory for the propane industry, Boston School District, just recently dealt it a major blow. In the 2015-2016 school year, the district started to transition its fleet to propane buses to reduce the impact of diesel. Much has changed in the ensuing six years: Boston Mayor Michelle Wu issued a local climate plan that charted out goals to fully transition the city’s buses by 2030 fully to zero-emissions technologies, phasing out all of its propane buses.

Today, Boston has a small electric fleet of 20 buses, still outnumbered by 80 propane buses. But most of its new purchases from here on will be EVs. Switching from the combustion engine to the EV is “a really different sensory experience,” said Hayes, the Boston School District deputy director of transportation. “The first thing people typically notice is that they sound like spaceships.”

A worker fiddles beneath the undercarriage of a raised school bus.
Bloomberg via Getty Images
A worker installs a coolant radiator to a repowered electric school bus at the Unique Electric Solutions facility in Holbrook, New York.

As futuristic as they may sound, according to a study by the nonprofit Public Interest Research Group, electrifying fleets is indeed an important step toward curbing the climate crisis: Replacing diesel school buses nationwide could avoid an average of 5.3 million tons of greenhouse gas emissions each year, the equivalent of permanently taking 1 million cars off the road.

School bus fleets provide a pilot to explore how EVs can work for other parts of the transportation sector. Heavy-duty vehicles make up just 6 percent of the vehicles on the road, but account for nearly 60 percent of smog-forming emissions and 55 percent of particle pollution from vehicles on the road. “School buses are really a perfect beachhead for moving to zero emissions,” said American Lung Association’s National Senior Director of Advocacy and Clean Air Will Barrett. “These are fixed routes, and they can charge in off hours when convenient, based on schedules.”

There are still plenty of skeptics out there who think EVs can’t compete with combustion engines. The propane industry is certainly trying to play into these fears, but it has so far struggled to capture its desired market share. Meanwhile, the EPA has received far more applications from schools wanting to shift their fleets to electric buses over other alternatives; in its first funding year, the agency reported that over 90 percent of its school bus program applications were for electric fleets.

In 2021, Montgomery County’s Carmen Cortez started driving an electric school bus. She told Vox the student complaints about the bad odors have stopped and her hands no longer reek of diesel. The EVs she drives are quiet, and she can actually hear kids’ voices instead of the rattling combustion engine. Sometimes, she can hear them too clearly, and she has to remind them to keep it down.

After two decades as a driver, Cortez was promoted to a role that includes training her coworkers to drive the district’s new electric school buses. She said she sometimes hears an ambivalence from them that an electric bus won’t function as well as a combustion engine. “I told my coworkers, ‘Just try one week. If you don’t like it, you can come back to diesel,’” she said in an interview. “I know they’re going to love it.”

Update, October 26, 4:45 pm ET: The story was originally published on October 5 and has been updated to include Carmen Cortez’s volunteer affiliation with EcoMadres, a Moms Clean Air Force program.

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